Electrolytic process.



PATENTED JAN. 3, 1906.

No;.779,384. v

O. PQTOWNSEND. ELEQTROLYTIGPR'OGESS. APPLIO'ATiON FILED my 11, 1904.

Patented January 3, 19L 5.

PATENT OFFICE.

CLINTON PAUL TOWNSEND, OF WASHINGTON, DISTRICT OF COLUMBIA.

ELECTROLYTIC PROCESS.

SPECIFICATION forming part of Letters Patent No. 779,384, dated January 3, 1905.

Original application filed April 12, 1902, Serial No. 102,582. Divided and this application filed May 11, 1904. Serial No. 207,490.

' of solutions, especially aqueous solutions of alkali-metal salts, and is directed to the recovery of a cathode product of electrolysis.

According to the processaproduct or products of the electrolysis, whether primary or secondary, is liberated in the presence of a liquid which is substantially immiscible with and inert toward said product or products and which serves several important functions, hereinafter specified.

As a specific example of my process I will describe the electrolysis of an aqueous solution of sodium ohlorid to produce caustic soda and chlorin, referring to the accompanying drawings, wherein the figure is a transverse vertical section of one type of cell.

The cell shown comprises a central compartment 1, containing an anode or anodes 2 and one or more lateral or cathode compartments 3, shown as two in number, the lateral compartments being separated from the central compartment by cathodes 4 and diaphragms 5. The anodes 2, shown as two in number, may be plates of Acheson graphite, carried by a conductor-bar 2, also of graphite, or they may be of any other suitable construction and material. The diaphragms 5 are of asbestos or other suitable pervious material, supported between the perforated sheet-metal or wire-gauze cathodes I and the plates 6, which have numerous small perforations, ex cept at their upper portions. The plates 6, which may be of hard rubber, earthenware, hardened asbestos, or other suitable non-conducting material, serve to support the diaphragm and may be omitted if the diaphragm is of self-supporting material. The cathodes are shown as inclined slightly from the vertical; but such inclination is not essential.

7 7 represent plates, preferably of iron, adjacent and approximately parallel to the oathodes. These plates terminate a slight dis- 8 8 are coils suitably connected and employed for heating or cooling the liquid in the cell to maintain the temperature of the electrolyte at any desired point. Considerable economy of current can be effected by maintaining the electrolyte at a suitable temperature above normal.

As illustrated, the cathode-compartments 3 3 are somewhat deeper than the central or anode compartment 1 and are provided with valve-regulated drain-pipes 9 9, communicating with the main conduit 10.

In operation the central compartment is filled with sodium-chlorid solution, and a continuous flow is preferably maintained through this compartment from below upward, the inlet 11 and outlet 12 being provided for this purpose. The lateral compartments are filled to or above the top of the plates 7 with aliquid which is substantially immiscible with and inert toward the cathode product, which product in the present instance is sodium hydrate. It is important that the liquid used in the lateral compartments should be of such character as to separate readily from the caustic and that it should be so inert with respect to the caustic that it will not undergo any rapid injurious change or modification in use. Of such liquid the non-saponifying oils may be taken as an example. Upon the passage of the current chlorin is liberated at the anode and sodium at the cathode. The chlorin escapes from the cell and may be collected and used as desired. The sodium is set free at the cathode in the presence of the inert immiscible liquid and is in part or entirely oxdrogen which results from the reaction cscapes upward through the narrow space between the cathodes and the plates 7, thereby inducing a strong circulation of the oil, which further aids in detaching the globules of caustic solution, thereby removing them quickly from the field of the electrolytic action.

The use of an inert liquid immiscible with the cathode product for the purpose of collecting such product effects many important advantages, as follows:

First. The product is formed and collected under a seal of said immiscible liquid and is thereby protected from all effects due to the contact of atmospheric gases. 1n the case of caustic soda, for instance, the sealing liquid prevents the production of sodium carbonate. It also prevents the production of carbonates of such metals as calcium and magnesium, which may be present in an unpurified brine and which would act to obstruct the diaphragm and gradually to reduce its porosity. It also prevents evaporation of the liquid which carries the product in solution and consequent deposition therefrom in the diaphragm or on the cathode of the less soluble constituents.

Second. lt effects the positive removal of the product from the electrode, an effect probably due in part at least to the difference in the adhesive power of the two liquids-as, for instance, the caustic solution and the mineral oil-for the material of the electrode. For instance, oil adheres closely to such sur faces, and it follows that the caustic solution, being unable to displace the oil, assumes at once the form of a globule and freely detaches itself from the surface. Since the amount of diffusion of one liquid into another is dependent upon the time during which they remain in contact, this rapid removal of the caustic through the agency of the oil is most effective in preventingdifl'usion of the caustic into the liquid in the anode-compartment.

Third. This removal of the caustic from the cathode is further aided by the fact that the hydrogen, which is a product of the reaction between the sodium and the water of the brine and which is set free concurrently with the production of the caustic, is liberated under the hydrostatic pressure of the oil instead of merely. expanding into an atmosphere. The hydrogen is compressed into bubbles which acquire a positive energy and direction of movement and greatly assist in detaching globules of caustic.

Fourth. The hydrogen, moving rapidly upward between the cathode and the plate 7, as before mentioned, imparts a rapid movement of circulation to the oil, which causes the oil to effectively and positively strip from the cathode the particles or globules of caustic solution. This rapid and useful movement of circulation is effected automatically and without extraneous assistance by the escaping hydrogen. The immiscible liquid therefore operating through its own adhesion to the cathode-surface, through the direction which it gives to the bubbles of hydrogen, and through its rapid movement of circulation, effects a practically instantaneous removal of the caustic from the surface of the cathode and from the field of electrolysis.

Fifth. The removal of the caustic from the cathode being effected in part by the hydrogen-bubbles escaping under the oil and in part by the stripping action of the circulating oil thereby induced, as above described, it follows that an increase of current density, by which both of these favorable effects are increased, will operate advantageously within certain limits. In practice I find that I am enabled to utilize current densities equal to or exceeding one ampere per square inch of cathode area with a high degree of efficiency, thus giving to the apparatus a very large capacity.

Sixth. During the relatively slow downward movement of the oil in the large compartment between the plate 7 and the cellwall the caustic carried by the oil is permitted to separate therefrom and is deposited in the lower portion of the cell and in the drainage system, whence it is Withdrawn as desired. The caustic is thus automatically deposited as formed out of the circulating path of the oil and out of the field of electrolytic action and is positively insulated from the electrolytic field.

Seventh. The oil further acts in a marked degree to protect the diaphragm from the products of the electrolysis. I find that a fibrous material of vegetable or animal origin may be employed and that the film of oil which covers or coats the fiber serves to a large extent to prevent contact therewith of the products of electrolysis, and hence to prevent their corrosive action.

Eighth. The oil affords a convenient means for regulating the rate of flow of the electrolyte through the diaphragm, and hence the concentration of caustic solutions produced at any particular current density. By raising or lowering the oil-level the amount of percolating liquid may be decreased or increased at will, and this effect may be supplemented by a variation in the level of the liquid in the anode compartment. If the rate of flow through the diaphragm be greatly diminished, the caustic is seen to be detached from the cathode in the form of flakes or flocculent masses or particles. 7

Ninth. The oil serves to positively support the diaphragm, and particularly those portions of the same which lie between the meshes of the cathode, and which therefore do not derive support therefrom. The tendency of the diaphragm to yield to the pressure of the liquid in the anode-compartment and to become perforated is thereby obviated.

Tenth. The hydrostatic pressure of the anode liquor varies from top to bottom of the diaphragm, and hence the percolation through portions of the diaphragm at dilferent levels would vary through wide limits in the absence of a balancing hydrostatic pressure. The effect of the balancingor partially balancing hydrostatic pressure of the oil is to compensate in part for such differences and to equalize the flow through different portions of the diaphragm.

Eleventh. The heating or cooling means for varying the temperature of the oil, and hence of the electrolyte, afford a convenient means for control in this respect.

It is to be understood that the foregoing statement of advantages is merely illustrative and is not to be construed as in any way limiting the scope of my process as defined in the claims.

In operating the cell I have noted a very marked storage effect, the yield at first being low, but rising rapidly to figures closely approximating those required by theory. On ceasing to pass current through the cell a strong secondary current appears, apparently due to the oxidation of sodium which had been deposited upon the cathode and protected from oxidation. This secondary current persists for a long period, and caustic-soda solution is delivered from the cell during the whole of such period. In case it is desired to interrupt the passage of current through the cell the electrical connections may be so changed as to cause this secondary current from two or more cells to pass through other cells, whereby such current is employed to produceai useful effect. Such procedure should not be permitted to continue too long, however, as some oxidation or solution of the cathode may occur.

The apparatus herein described is claimed in my copending application, Serial No. 207,227, filed May 10, 1904.

This application is a division of my application, Serial No. 102,582, filed April 12, 1902.

I claim 1. The process of electrolyzing solutions, which consists in passing an electric current through the solution to a cathode, and recovering a cathode product of electrolysis by means of a liquid which is substantially immiscible with and inert toward said product, as set forth.

2. The process of electrolyzing solutions of alkali-metal salts, which consists in passing an electric current through the solution to a cathode, converting the alkali metal deposited on said cathode into a compound, and recovering said compound by means of a liquid which is substantially immiscible with and inert toward the compound, as set forth. 6o

stantially immiscible with and inert toward said product, as set forth.

4. The process of electrolyzing solutions of alkali-metal salts, which consists in passing an cathode, and recoveringa cathode product of electrolysis by means of a non-saponifying oil, as set forth.

6. The process of electrolyzing solutions of alkali-metal salts, which consists in passing an electric current through the solution and a diaphragm to a cathode, converting the alkali metal deposited on said cathode into a com pound, and recovering said compound by means of a non-saponifying oil, as set forth.

7. The process of electrolyzing solutions, which consists in interposing a diaphragm and a pervious cathode between a body of the solution and a body of a liquid which is substantially immiscible with and inert toward a cathode product of the electrolysis, and passing an electric current through said solution and diaphragm to said cathode, whereby said product is removed from the field of electrolysis, as set forth.

8. The processof electrolyzing solutions of alkali-metal salts, which consists in interposing a diaphragm and a pervious cathode between a body of the solution and a body of a liquid which is substantially immiscible with and inert toward the alkali-metal compound produced, passing an electric current through said solution and diaphragm to said cathode, converting the alkali metal deposited on said cathode into a compound, and recovering said compound by means of said liquid, as set forth.

9'. The process of electrolyzing solutions, which consists in interposing a diaphragm and a pervious cathode between a body of the solution and a body of a non-saponifying oil, and passing an electric current through said solution and diaphragm to said cathode, whereby a product is removed from the field of electrolysis, as set forth.

10. The process of electrolyzing solutions of alkali-metal salts,which consists in interposing a diaphragm and a pervious cathode between a body of the solution and a body of a nonsaponifying oil, passing an electric current through said solution and diaphragm to said cathode, converting the alkali metal deposited on said cathode into a compound, and recovering said compound by means of said oil, as set forth.

I O U &

11. The process of electrolyzing solutions, which consists in passing an electric current through the solution to a cathode, recovering a cathode product of electrolysis by means of a liquid which is substantially immiscible with and inert toward said product, and cir. culating said liquid in contact with said cathode, as set forth.

12. The process of electrolyzing solutions, which consists in passing an electric current through the solution to a cathode, recovering a cathode product of electrolysis by means of a liquid which is substantially immiscible with and inert toward said product, and circulating said liquid in contact with said cathode by means of a gaseous product of the electrolysis, as set forth.

13. The process of electrolyzing solutions of alkali-metal salts, which consists in passing an electric current through the solution to a cathode, converting the alkali metal deposited on said cathode into a compound, recovering said compound by means of a liquid which is substantially immiscible with and inert toward the compound, and circulating said liquid in contact with said cathode by means of a gaseous product of the electrolysis, as set forth.

14c. The process of electrolyzing solutions, which consists in passing an electric current through the solution and a diaphragm to a cathode, recovering a cathode product of electrolysis by means of a liquid which is substantially immiscible with and inert toward said product, and circulating said liquid in contact with said cathode, as set forth.

15. The process of electrolyzing solutions, which consists in passing an electric current through the solution and a diaphragm to a cathode, recovering a cathode product of electrolysis by means of a liquid which is substantially immiscible with and inert toward said product, and circulating said liquid in contact with said. cathode by means of a gaseous product of the electrolysis, as set forth.

16. Theprocessof electrolyzingsolutionsof alkali-metal salts, which consists in passing an electric current through the solution and a diaphragm to a cathode, convertingthe alkali metal deposited on said cathode into a compound, recovering said compound by means of a liquid which is substantially immiscible with and inert toward the compound, and circulating said liquid in contact with said cathode by means of a gaseous product of the electrolysis, as set forth.

17. The process of clectrolyzing solutions, which consists in passing an electric current through the solution and a diaphragm to a cathode, recovering a cathode product of electrolysis by means of a liquid which is substantially immiscible with and inert toward said product, and circulating said liquid rapidly upward along said cathode and slowly downward at a distance from said cathode, as set forth.

18. The process of electrolyzing solutions, which consists in passing an electric current through the solution and a diaphragm to a cathode, recovering a cathode product of electrolysis by means of a liquid which is substantially immiscible with and inert toward said product, and circulating said liquid rapidly upward along said cathode and slowly downward at a distance from said cathode by means of a gaseous product of the electrolysis, as set forth.

19. The process of electrolyzing solutions of alkali-metal salts, which consists in passing an electric current through the solution and a diaphragm to a cathode, converting the alkali metal deposited on said cathode into a compound, recovering said compound by means of a liquid which is substantially immiscible with and inert toward the compound, and circulating said liquid rapidly upward along said cathode and slowly downward at a distance from said cathode by means of a gaseous product of the electrolysis, as set forth.

20. The process of electrolyzing solutions, which consists in interposing a diaphragm and a pervious cathode between a body of the solution and the body of a liquid which is substantially immiscible with and inert toward a cathode product of the electrolysis, passing an electric current through said solution and diaphragm to said cathode, whereby said product is removed from the field of electrolysis, and controlling the temperature of the electrolyte by suitably varying the temperature of said liquid, as set forth.

21. The process of electrolyzing solutions of alkali-metal salts, which consists in interposing a diaphragm and a pervious cathode between a body of the solution and a body of a liquid which is substantially immiscible with and inert toward the alkali-metal compound produced, passing an electric current through said solution and diaphragm to said cathode, converting the alkali metal deposited on said cathode into a compound, recovering said compound by means of said liquid, and controlling the temperature of the electrolyte by suitably varying the temperature of said liquid, as set forth.

22. The process of electrolyzing solutions, which consists in liberating a product of the electrolysis in the presence of a liquid which is substantially immiscible with and inert toward said product, as set forth.

23. The process of electrolyzing solutions of alkali-metal salts, which consists in liberating and oxidizing the alkali metal in the presence of a non-saponifying oil, as set forth.

242. The process of electrolyzing aqueous solutions of alkali-metal salts, which consists in liberating the alkali metal in the presence of a liquid which is substantially immiscible with and inert toward alkali-metal hydroXids, and oxidizing said metal by the water in the solution, as set forth.

25. The process of electrolyzing aqueous solutions of alkali-metal salts, which consists in liberating the alkali metal in the presence of a non-saponifying oil, and oxidizing said metal by the water in the solution, as set forth.

26. The process of electrolyzing aqueous solutions of alkali-metal salts, which consists in interposing a diaphragm and a pervious cathode between a body of the solution and a body of a liquid which is substantially immiscible with and inert toward alkali-metal hydroXids, passing an electric current through said solution and diaphragm to said cathode, oxidizing the alkali metal deposited on said cathode by the water in said solution,and withdrawing the alkali-metal hydroxid through said body of liquid, as set forth.

27. The process of electrolyzing aqueous solutions of alkali-metal salts, which consists in interposing a diaphragm and a pervious cathode between a body of the solution and a body of a non-saponifying oil, passing an electric current through said solution and diaphragm to said cathode, oxidizing the alkali metal deposited on said cathode by the water in said solution, and removing the alkali-metal hydroXid through said body of oil, as set forth.

In testimony whereof I afiix my signature in presence of two witnesses.

CLINTON PAUL TOWNSEND.

Witnesses:

RoBT. E. J. CoRooRAN, ELoN H. HOOKER. 

